Computer Networks and Internet Concepts
What this domain tests
This domain tests how devices communicate and how the Internet delivers services. Expect questions on network types, topologies, devices, addressing, protocols, and URL structure.
Core rules
- Network types by scale: PAN (personal), LAN (building/campus), MAN (city), WAN (countries/global).
- Topologies: bus (one backbone), star (central switch/hub), ring (closed loop), mesh (many redundant links). Star is common in LANs; mesh is robust but cabling-heavy.
- Devices: hub broadcasts to all ports; switch forwards by MAC address; router forwards between networks by IP address; modem converts signals for the ISP link; repeater regenerates signals.
- Media: twisted-pair copper, coaxial cable, and fibre-optic cable (high bandwidth, immune to electromagnetic interference).
- An IP address identifies a device on a network; a MAC address is a hardware address. DNS resolves domain names to IP addresses; DHCP assigns IP addresses automatically.
- Protocols: HTTP/HTTPS for web, FTP for file transfer, SMTP for sending mail, POP3/IMAP for receiving mail, TCP (reliable, connection-oriented) and UDP (fast, connectionless).
- A URL contains a protocol, domain name, and path: https://www.example.com/page.html.
Worked example
In https://www.example.com/page.html, https is the protocol, www.example.com is the domain name resolved by DNS, and /page.html is the resource path. HTTPS uses encryption, normally on port 443, while HTTP uses port 80. If DNS failed, the browser could not convert the domain name into an IP address, so the page would not load even if the web server were running.
Traps
- Confusing a hub (broadcast) with a switch (MAC-based forwarding).
- Confusing a router with a modem.
- Mixing DNS (name-to-IP) with DHCP (automatic IP assignment).
- Saying HTTP is secure; HTTPS is the encrypted version.
- Treating an IP address and a MAC address as the same thing.